Endoprosthesis having aligned legs for ease of cannulation

ABSTRACT

The present disclosure is directed to a branched endoprosthesis comprising a graft component and at least one support component. In various embodiments, the branched endoprosthesis comprises a body portion and a plurality of leg portions, wherein the legs are in an aligned configuration for ease of cannulation. In various embodiments, at least one leg is in an open configuration for ease of cannulation. Cannulation methods are also taught.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.13/740,457, filed Jan. 14, 2013, now U.S. Pat. No. 9,687,371, grantedJun. 27, 2017, entitled ENDOPROSTHESIS HAVING ALIGNED LEGS FOR EASE OFCANNULATION, which claims priority to and the benefit of U.S.Provisional Patent Application Ser. No. 61/598,773, entitledENDOPROSTHESIS HAVING ALIGNED LEGS FOR EASE OF CANNULATION and filedFeb. 14, 2012, all of which are incorporated by reference herein intheir entireties.

FIELD

The present disclosure relates to improved branched endoprostheses fortreating disease of the vasculature.

DISCUSSION OF THE RELATED ART

Branched endoprostheses are commonly used for treating disease of thevasculature. By way of example, bifurcated stent grafts may be used inthe treatment of abdominal aortic aneurisms, which generally affect theabdominal aorta and may extend down into the iliac arteries.

A bifurcated stent graft used in the treatment of abdominal aorticaneurisms is generally inserted through an iliac artery up into theabdominal aorta, where it is deployed and anchored. The graft'sipsilateral leg extends down into the iliac artery through which thegraft was inserted. On the other hand, the graft's contralateral legdoes not extend below the abdominal aorta.

To extend the graft's contralateral leg down into the other iliacartery, a second stent graft is inserted through that other iliac arteryover a guidewire and attached to the original graft's contralateral leg.Although endoscopic imaging, radiopaque markers, etc. may be employed,this cannulation process is often difficult given not only the tortuousvasculature, but also structural biases within the original stent graftangling the legs apart in a Y configuration so as to face them towardtheir respective iliac arteries.

Generally speaking, cannulation of contralateral legs of branchedendoprostheses presents difficulties for medical practitioners whoheretofore have had to rely heavily on trial and error. There is thus aneed in the art for bifurcated endoprostheses that are better adaptedfor ease of cannulation.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this specification, illustrate embodiments of the disclosure,and together with the description serve to explain the principles of thedisclosure, wherein:

FIGS. 1A-1E illustrate the progressive deployment of a branchedendoprosthesis having two legs in an aligned configuration in accordancewith one embodiment of the present disclosure; and

FIGS. 2A and 2B illustrate a tether configured to maintain contralateraland ipsilateral legs of a bifurcated stent graft in an alignedconfiguration in accordance with one embodiment of the presentdisclosure.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Persons skilled in the art will readily appreciate that various aspectsof the present disclosure may be realized by any number of methods andapparatuses configured to perform the intended functions. Stateddifferently, other methods and apparatuses may be incorporated herein toperform the intended functions. It should also be noted that theaccompanying drawing figures referred to herein are not all drawn toscale, but may be exaggerated to illustrate various aspects of thepresent disclosure, and in that regard, the drawing figures should notbe construed as limiting. Finally, although the present disclosure maybe described in connection with various principles and beliefs, thepresent disclosure should not be bound by theory.

In addition, the present disclosure will be described primarily withreference to treating disease of the abdominal aorta, however, thedisclosure and principles may be applied to other disease of thevasculature, including, for example, any disease where a larger vesseland one or more branch vessels are to be treated. Likewise, although thedisclosure will be described primarily with reference to bifurcatedendoprostheses, it should be understood that the disclosure andprinciples may be applied to endoprostheses having any number ofbranches, for example, 2, 3, 4 or more.

The present disclosure is directed toward a branched endoprosthesis. Anendoprosthesis may comprise a graft component and at least one supportcomponent, such as in a stent graft.

A graft component is generally any abluminal (i.e., outer, vesselsurface) or luminal (i.e., inner, blood flow surface) coveringconfigured to partially or substantially cover one or more supportcomponents.

In various embodiments, a graft component comprises ePTFE. However,other useful materials for the graft component may comprise one or moreof nylons, polycarbonates, polyethylenes, polypropylenes,polytetrafluoroethylenes, polyvinyl chlorides, polyurethanes,polysiloxanes, and other biocompatible materials.

A graft component is fixedly secured or otherwise coupled at a single ora plurality of locations to the abluminal or luminal surface of thesupport component, for example, using one or more of taping, heatshrinking, adhesion and other processes known in the art. In someembodiments, a plurality of graft components are used and may be coupledto both the abluminal and luminal surfaces of the support component(s).In other embodiments, a plurality of graft components “sandwich” thesupport component(s), the graft components being attached to each other.

In various embodiments, a support component has dimensions appropriatefor the given treatment and may provide structural support for the graftcomponent of the endoluminal device and/or the vasculature to betreated. A support component may be a stent comprised either of a wirehaving a helical configuration or be comprised of one or a plurality ofrings. Among other configurations, the wire or a ring itself may belinear or have a sinusoidal or zig-zag pattern. Still another supportcomponent may be cut from a tube and have any pattern suitable for thetreatment.

The support component can be comprised of a shape-memory material, suchas nitinol. In other embodiments, however, the support component may becomprised of other materials, self-expandable or otherwise expandable(e.g., with a conventional balloon catheter or spring mechanism), suchas various metals (e.g., stainless steel), alloys and polymers.

In various embodiments, the branched endoprosthesis comprises a bodyportion and at least two leg portions, which may be defined by the graftand/or support components. The cross-section of the body portion may becircular, ovoidal, or have polygonal features with or without curvedfeatures. The cross-sectional shape of the body portion may be eithersubstantially constant or variable along its axial length. In likemanner, the cross-sectional surface area of the body portion may beeither substantially constant or variable along its axial length. In anembodiment of a bifurcated endoprosthesis, the body portion'scross-section is substantially circular at its distal end but tapers tohave an ovoidal rectangular cross-section with a smaller cross-sectionalsurface area in its bifurcation region.

As noted previously, a branched endoprosthesis comprises two or more legportions branched off of and in luminal communication with the bodyportion.

In various embodiments, the axial length(s) of the contralateral leg(s)(i.e., the leg(s) for cannulation) is/are substantially shorter that theaxial length of the ipsilateral leg.

In various embodiments, a branched endoprosthesis possesses one or morestructural biases angling the leg portions apart, for instance in a Yconfiguration, so as to face or direct them toward their respectivevessels to be treated. The structural bias may arise from either or bothof a graft component and a support component.

In various embodiments, at least two leg portions are in an alignedconfiguration for ease of cannulation. The alignment may be permanent orin some embodiments, temporary until after guidewire insertion orcannulation. In various embodiments, aligning a plurality of legportions requires overcoming the aforementioned structural bias. As usedherein, “align” or “aligned” means aligned axially, drawn together,parallel, and/or the state of the plane of the contralateral leg'sopening being perpendicular to the axis of the ipsilateral leg. For theavoidance of doubt, “align” may, but does not necessarily implicatealignment along or with respect to any anatomical or endoprosthesisaxis.

In an embodiment, alignment is accomplished by commonly sheathing thelegs and only removing the sheath after guidewire insertion orcannulation. For example, and with reference to the accompanyingdrawings, FIG. 1A illustrates an outer sheath 110 enclosing a bifurcatedstent graft (not shown) to be delivered via a guidewire 120 and atubular element 130.

A “sheath” may be comprised of one or more of nylons, polycarbonates,polyethylenes, polypropylenes, polytetrafluoroethylenes, polyvinylchlorides, polyurethanes, polysiloxanes, stainless steels, or otherbiocompatible materials. A sheath can be a sleeve or an introducersheath. In yet other embodiments, a sheath is a tubular element, as thatterm has been defined herein.

The term “tubular element” includes any longitudinally extendingstructure with or without a lumen therethrough, for example a catheter.Thus, tubular elements include but are not limited to tubes with lumens,solid rods, hollow or solid wires (e.g., guidewires), hollow or solidstylets, metal tubes (e.g., hypotubes), polymer tubes, pull cords ortethers, fibers, filaments, electrical conductors, radiopaque elements,radioactive elements and radiographic elements. Tubular elements can beof any material and can have any cross-sectional shape including but notlimited to profiles that are circular, oval, triangular, square, polygonshaped or randomly shaped.

Turning now to FIG. 1B, outer sheath 110 may be partially removed fromthe distal half of bifurcated stent graft 140, revealing a closed innersheath 150 which aligns the contralateral and ipsilateral legs ofbifurcated stent graft 140.

With reference to FIG. 1C, anchors 160 at the distal end of bifurcatedstent graft 140 may be retracted for adjusting placement of bifurcatedstent graft 140. Note that in this embodiment, inner sheath 150 stillmaintains the contralateral and ipsilateral legs of bifurcated stentgraft 140 in an aligned configuration.

As shown in FIG. 1D, inner sheath 150 may be partially removed from thedistal portion of bifurcated stent graft 140, but not removed at itsproximal end, thus maintaining the contralateral and ipsilateral legs ofbifurcated stent graft 140 in an aligned configuration until, as shownin FIG. 1E, a guidewire 170 has been inserted into the contralateral legof bifurcated stent graft 140 or cannulation of the contralateral leghas occurred.

Notwithstanding the foregoing non-limiting example, various physical andchemical coupling methods and apparatuses may be used in the alignment,including but not limited to various removable tethers, restraints,adhesives, hooks, magnets, nanostructure binding agents, etc.

FIGS. 2A and 2B illustrate a tether 245 configured to maintaincontralateral and ipsilateral legs of a bifurcated stent graft 240 in analigned configuration in accordance with one embodiment of the presentdisclosure. In various embodiments, tether 245 releasably couples andretains contralateral and ipsilateral legs of bifurcated stent graft 240including, in various embodiments, during movement of bifurcated stentgraft 240 between delivery and deployed configurations.

In various embodiments, an outer sheath extends around and maintainsbifurcated stent graft 240 in a delivery configuration. In suchembodiments, the outer sheath can have opposite sides releasably heldtogether to maintain bifurcated stent graft 240 in the deliveryconfiguration. In such embodiments, the outer sheath can have aplurality of holes through which an elongated member extends toreleasably hold the opposite sides of the outer sheath together. In suchembodiments, tether 245 can be an extension of the elongated member.

An end tail of tether 245 can be tucked under undeployed portions of asurrounding sleeve and/or routed under, or otherwise secured to, one ormore apices of a support component. Tether 245 can be routed in variousconfigurations, for example between an apice of a support component andthe wall of a graft component. In general, an end tail of tether 245 isrouted so as to be retained, while not presenting high pullout forces.

Tether 245 can comprise a thread, fiber, or filament, for example onethat is polymeric in nature. In other embodiments, tether 245 comprisesa wire, having a high columnar strength. In yet other embodiments,tether 245 is a tubular element, as that term has been defined herein.

In various embodiments, tether 245 is adjustable separate from beingpulled out. In various embodiments, tether 245 is pulled out separatefrom deployment of bifurcated stent graft 240.

In various embodiments, tethering eliminates the need for an innersheath, thus reducing the crossing profile, for example to less than 18Fr, less than 16 Fr, or less than 14 Fr.

Adhesives may comprise those that are soluble for releasing the legsfrom their aligned configuration after guidewire insertion orcannulation. A single hook or a plurality of hooks or hook and loopfasteners (e.g., a Velcro® type configuration) may be used. A magnet maybe inserted via catheter into the one leg to draw another leg intoalignment with it. Nanostructure binding agents useful in the alignmentmay comprise DNA, RNA, etc.

Additional features and elements may be used in connection with thepresent disclosure. In one embodiment for example, at least one leg ismaintained in an open configuration for ease of cannulation. This may beaccomplished, for example, by incorporating an independent wire or ring,such as a support component as described herein, at the distal end ofthe leg. In an embodiment, a plurality of serially aligned supportcomponents are adapted to hold the contralateral leg open forcannulation. In yet another embodiment, one or more radiopaque and/orechogenic markers are incorporated into the branched endoprosthesis, forexample, along, or at the distal end of, the contralateral leg.

A cannulation method comprises delivering a branched stent graftenclosed by an outer sheath into a branch artery and to the lumen of atrunk artery via a guidewire and a tubular element, for example at adistal end of a catheter.

In various embodiments, the outer sheath is partially removed from thebody portion of the branched stent graft extending into the trunkartery, thus partially deploying the graft and exposing an inner sheathwhich aligns one or more contralateral legs with the ipsilateral leg ofthe branched stent graft.

Next, placement of the branched stent graft may be adjusted, forexample, by retracting anchors at the distal end of the body portion ofthe branched stent graft, rotating and/or advancing or reversing theguidewire and/or the tubular element, and thereafter fully deploying theanchors into the sides of the trunk artery.

Once the branched stent graft is determined to be properly positioned, asecond guidewire may be inserted into a contralateral leg of thebranched stent graft via a second branch artery in communication withthe trunk artery. Cannulation of the contralateral leg may thereafteroccur.

Once the second guidewire has been inserted into the contralateral leg,the inner sheath may be fully removed, thus no longer necessarilymaintaining the contralateral and ipsilateral legs of the branched stentgraft in an aligned configuration.

Yet another method comprises providing a branched stent graft comprisinga body portion, an ipsilateral leg portion, and a contralateral legportion. In this particular embodiment, the leg portions may be biasedto be angled apart in a Y configuration. Next, the bias is temporarilyovercome by aligning the leg portions using one or more of themechanisms described herein.

In accordance with this method, the branched stent graft is delivered toa trunk vessel via an ipsilateral branch vessel. The body portion andthe ipsilateral leg portion of the branched stent graft are deployed inthe trunk vessel and the ipsilateral branch vessel respectively. Usingthe alignment of the leg portions, a distal opening of the contralateralleg portion is located to facilitate its cannulation. Finally, the legportions are allowed to return to the initial Y configuration.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present disclosurewithout departing from the spirit or scope of the disclosure. Thus, itis intended that the embodiments described herein cover themodifications and variations of this disclosure provided they comewithin the scope of the appended claims and their equivalents.

Numerous characteristics and advantages have been set forth in thepreceding description, including various alternatives together withdetails of the structure and function of the devices and/or methods. Thedisclosure is intended as illustrative only and as such is not intendedto be exhaustive. It will be evident to those skilled in the art thatvarious modifications can be made, especially in matters of structure,materials, elements, components, shape, size and arrangement of partsincluding combinations within the principles of the disclosure, to thefull extent indicated by the broad, general meaning of the terms inwhich the appended claims are expressed. To the extent that thesevarious modifications do not depart from the spirit and scope of theappended claims, they are intended to be encompassed therein.

What is claimed is:
 1. A method comprising: providing a branchedendoprosthesis comprising a body, a first leg, and a second leg, whereina restraint extends between and aligns the first and second legs;delivering the endoprosthesis to a position within a vessel in adelivery configuration; deploying the endoprosthesis to a partiallydeployed state such that the restraint maintains the alignment of thefirst and second legs; maintaining the first and second leg alignmentwith the restraint such that movement of the first leg relative to thesecond leg is restrained while the endoprosthesis is in the partiallydeployed state; cannulating the second leg while the restraint maintainsthe alignment of the first leg with the second leg; and releasing therestraint between the first and second legs such that the first andsecond legs are free to angle apart.
 2. The method of claim 1, whereincannulating the second leg while the restraint maintains alignment ofthe first leg with the second leg includes inserting a guidewire intothe second leg.
 3. The method of claim 1, wherein the partially deployedstate includes the body being fully deployed.
 4. The method of claim 1,wherein the partially deployed state includes the second leg being fullydeployed.
 5. The method of claim 1, wherein the partially deployed stateincludes the first leg remaining undeployed.
 6. The method of claim 1,wherein deploying the endoprosthesis to the partially deployed stateincludes partially removing an outer sheath from a distal portion of theendoprosthesis.
 7. The method of claim 1, wherein the restraint is areleasable tether and releasing the tether includes deploying theendoprosthesis to a fully deployed state.
 8. The method of claim 1,wherein the restraint is coupled to and extends between exteriorsurfaces of the first and second legs.
 9. The method of claim 1, whereinthe restraint includes an end tail that is tucked under an undeployedportion of a sleeve surrounding the endoprosthesis.
 10. The method ofclaim 1, wherein the endoprosthesis includes a support component havinga plurality of apices, and wherein the restraint includes an end tailthat is routed under one or more of the plurality of apices.
 11. Themethod of claim 1, wherein the restraint includes a sheath that isdisposed about the first and second legs.
 12. The method of claim 1,wherein the restraint includes an adhesive.
 13. The method of claim 1,wherein the restraint includes one or more hook and loop fastenersassociated with the first and second legs.
 14. The method of claim 1,wherein the restraint includes one or more magnets associated with thefirst and second legs.
 15. The method of claim 1, wherein the restraintincludes a nanostructure binding agent.
 16. The method of claim 1,wherein the first and second legs are biased to extend at an angle fromone another.
 17. The method of claim 16, wherein the first and secondlegs are biased apart in a Y configuration when the first leg is notmaintained in alignment with the second leg by the restraint.
 18. Amethod comprising: providing an endoprosthesis that includes a bodyportion and a plurality of legs that are biased to be angled apart, theendoprosthesis having a removable restraint coupled thereto that extendsbetween the first and second legs and overcomes the bias and aligns theplurality of legs; delivering the endoprosthesis to a position with avessel while the bias of the first and second legs is overcome by theremovable restraint; partially deploying the endoprosthesis by removinga constraining sheath disposed about a first one of the plurality oflegs such that the restraint maintains the alignment of the first andsecond begs; cannulating the first one of the plurality of legs afterpartially deploying the endoprosthesis and while the bias of the firstand second legs remains overcome and the plurality of legs remainaligned by the removable restraint; and removing the removable restraintsuch that the bias of the plurality of legs causes the plurality of legsto angle apart.
 19. The method of claim 16, wherein the removablerestraint includes a tether that is coupled to and extends betweenexterior surfaces of the first and second legs.
 20. The method of claim16, wherein the removable restraint includes a sheath.